Thermoplastic Prepreg Systems
Litzler also offers systems for the manufacture of thermoplastic prepregs.
- The most common type applies the resin either as resin powder suspended in water slurry, or as resin dissolved in a solvent. In both cases, the fiber web is saturated with the slurry/solution, and then the carrier liquid is evaporated.
- In some cases depending on the resin and fiber, it is possible to apply the powdered resin directly to the fiber, with no liquid carrier.
- After the resin is applied and all liquid is removed, the coated fiber is preheated to the resin’s melt temperature and pulled through a heated die.
Thermoplastic machines feature many of the same machine components as the Solution or Hot Melt machines including:
- Fiber management and fiber spreading
- Litzler Automation control systems
- Edge trim and trim winding
In addition to the standard components, the Litzler Thermoplastic Tape Machines feature some unique attributes:
- Fiber Saturation/Fiber Impregnation
- The thermoplastic resin is mixed in a water suspension and recirculates through a dip station
- The stainless steel dip tank features mixing distribution manifolds and a series of dip rollers
- The fiber band is pulled through the dip bath to pick up the desired thermoplastic resin
- Infrared Oven is used to dry and remove the water without disturbing the resin that remains on the fiber
- After the water is removed, the resin is heated in an additional IR zone and then pulled into the precision Heated Die
- Heated Die – the machined and heated die sets the tape physical properties
Hot melt prepreg requires the resin to be pre-coated on to a carrier paper or plastic film. This is normally coated on a separate machine called a filmer. The filmers are available in three configurations:
- Knife over plate – standard on our 12” (300 mm) pilot lines
- Knife over roll – suitable for most applications
- Reverse roll – suitable for lowest areal weight applications
- Nip coater – suitable for direct saturation or on-line coating
The knife assemblies feature rigid designs to resist deflection and adjustable gap setting to reach areal weights down below 50 gsm.
Roll assemblies feature 0.0002 up to 0.00005” TIR designs with the same construction techniques as Litzler Metering Rolls and Litzler Compaction Rolls – large diameter to resist deflection and double-walled for excellent heat transfer and uniformity
Filmers feature all of the same functions as other Litzler composites machines:
- Unwinds for the paper or film web to be coated
- Tension control
- Liners unwinds
- Web cooling (rolls or plates)
- Edge trim and trim winding
- Rewind system
- Litzler Automation Control system
Litzler offers pilot machines for all of the above applications:
- Com-preg – 24” narrow vertical tower for solvent/solution applications – structural composites or copper clad laminates machines that feature all of the same precision as a full size production machine – available with Opti-flow or Perfect Radiant oven systems
- Hot melt – 12” (300 mm) pilot Hot Melt UD machines
- Drum Winder – (1725 or 1726 photo) the drum winder is a lab scale machine that impregnates a single tow and uses a progressive heated drum to make a single tape. The width and length of the tape depends on the size of the heated drum – typically 36” diameter and 20” wide to produce a 9’ long sample tape
Machine Upgrades/Machine Modernization
Litzler provides complete machines and we also supply machine upgrades for our own machines and any existing machine. Upgrades can include any of the components listed above to improve existing machines or to add speed to an existing machine. Litzler Automation is also available to modernize older control systems to the latest PLC and drive designs.